of its relations, is subjected to compression, while at the same time displacements of intensity among its elements force a psychic revaluation of this material. The displacements which we have considered were shown to be substitutions of one idea for another, the substitute being in some way connected with the original by associations, and the displacements were put to the service of condensation by virtue of the fact that in this manner a common mean between two elements took the place of these two elements in the formation of the dream. We have not yet mentioned any other kind of displacement. But we learn from the analyses that another exists, and that it manifests itself in a change of the verbal expression employed for the thought in question. In both cases we have displacement following a chain of associations, but the same process takes place in different psychic spheres, and the result of this displacement in the one case is that one element is substituted for another, while in the other case an element exchanges its verbal expression for another.
This second kind of displacement occurring in dream formation not only possesses great theoretical interest, but is also peculiarly well fitted to explain the semblance of phantastic absurdity in which the dream disguises itself. Displacement usually occurs in such a way that a colourless and abstract expression in the dream-thought is exchanged for one that is visual and concrete. The advantage, and consequently the purpose, of this substitution is obvious. Whatever is visual is capable of representation in the dream, and can be wrought into situations where the abstract expression would confront dream representation with difficulties similar to those which would arise if a political editorial were to be represented in an illustrated journal. But not only the possibility of representation, but also the interests of condensation and of the censor, can be furthered by this change. If the abstractly expressed and unwieldy dream-thought is recast into figurative language, this new expression and the rest of the dream material are more easily furnished with those identities and cross references, which are essential to the dream activity and which it creates whenever they are not at hand, for the reason that in every language concrete terms, owing to their evolution, are more abundant in associa-